General cargo transported by means of wheeled carriages -- railway waggons and road trucks -- is not well suited for transportation in ships. A considerable amount of handling is required, which means that the ship will be tied up in port for a long time. The traditional manner in shifting cargo between railway waggons and a ship, and vice versa, is to have railway tracks running parallel with the quay, and then, step by step moving the waggons of a train past a ship moored at the quay. Different kinds of goods and different destinations will have to be considered when stowing the ship, and much shunting of waggons may have to be done in order to present the goods in proper order.
Ships are nowadays, to an increasing extent, fitted for the transportation of uniform cargo units, in the first hand shipping containers, and if the cargo, beforehand is stowed into such containers the loading and unloading of a ship may be arranged in a reduced time. Certain pieces of cargo are not suited for transportation in shipping containers, i.a due to the costs, and also the handling of individual containers will require some time.